Flow analysis: support functions whose bodies are expressions.

Change-Id: I01a66fb2c897e0cabbdfb4b7423cab53291b3adf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/113947
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Paul Berry <[email protected]>

Author: stereotype441

pkg/analysis_server/test/services/completion/dart/keyword_contributor_test.dart

@@ -2177,4 +2177,12 @@ class KeywordContributorWithNnbdTest extends KeywordContributorTest {
     super.setupResourceProvider();
     createAnalysisOptionsFile(experiments: [EnableString.non_nullable]);
   }
+
+  @override
+  @failingTest
+  test_ifOrForElement_forElement() {
+    // TODO(paulberry): this test is failing due to lack of support for flow
+    // analysis of "for" elements.
+    return super.test_ifOrForElement_forElement();
+  }
 }

pkg/analyzer/lib/src/dart/resolver/flow_analysis_visitor.dart

@@ -124,7 +124,7 @@ class FlowAnalysisHelper {
     }
   }
 
-  void blockFunctionBody_enter(BlockFunctionBody node) {
+  void functionBody_enter(FunctionBody node) {
     _blockFunctionBodyLevel++;
 
     if (_blockFunctionBodyLevel > 1) {
@@ -145,7 +145,7 @@ class FlowAnalysisHelper {
     }
   }
 
-  void blockFunctionBody_exit(BlockFunctionBody node) {
+  void functionBody_exit(FunctionBody node) {
     _blockFunctionBodyLevel--;
 
     if (_blockFunctionBodyLevel > 0) {

pkg/analyzer/lib/src/generated/resolver.dart

@@ -3503,12 +3503,12 @@ class ResolverVisitor extends ScopedVisitor {
   @override
   void visitBlockFunctionBody(BlockFunctionBody node) {
     try {
-      _flowAnalysis?.blockFunctionBody_enter(node);
+      _flowAnalysis?.functionBody_enter(node);
       inferenceContext.pushReturnContext(node);
       super.visitBlockFunctionBody(node);
     } finally {
       inferenceContext.popReturnContext(node);
-      _flowAnalysis?.blockFunctionBody_exit(node);
+      _flowAnalysis?.functionBody_exit(node);
     }
   }
 
@@ -3788,6 +3788,7 @@ class ResolverVisitor extends ScopedVisitor {
       return;
     }
     try {
+      _flowAnalysis?.functionBody_enter(node);
       InferenceContext.setTypeFromNode(node.expression, node);
       inferenceContext.pushReturnContext(node);
       super.visitExpressionFunctionBody(node);
@@ -3801,6 +3802,7 @@ class ResolverVisitor extends ScopedVisitor {
       }
     } finally {
       inferenceContext.popReturnContext(node);
+      _flowAnalysis?.functionBody_exit(node);
     }
   }
 

pkg/front_end/test/flow_analysis/type_promotion/data/conditional.dart

@@ -16,3 +16,6 @@ void conditional_then(bool b, Object x) {
   b ? ((x is num) || (throw 1)) : 0;
   x;
 }
+
+int conditional_in_expression_function_body(Object o) =>
+    o is int ? /*int*/ o : 0;